This invention relates to transducers. More particularly, the invention relates to transducer assemblies which apply increased amounts of power to the earth around the transducer assemblies to obtain an enhanced recovery of oil from the earth.
As oil wells now in existence are being depleted, it has become increasingly difficult to discover new sources of oil and to recover the oil from these new sources. The oil being discovered is generally at increased depths under the earth""s surface. Furthermore, the oil is often viscous and is disposed at positions under the earth""s surface where it cannot be easily recovered. For these and other reasons, it has become increasingly difficult to recover as much oil from the earth as would otherwise be desired.
Increased forces have had to be applied by the transducers to the earth around the transducers to separate the oil and recover the separated oil from the earth. The problems have been magnified because the characteristics of the earth, even at closely spaced positions, vary. These variable characteristics, even at closely spaced positions, prevent the transducers from operating efficiently to separate and recover the oil from positions below the earth""s surface.
Transducers now in use are disposed below the earth""s surface and are vibrated to separate the oil from the earth and to recover the separated oil. The recovery of the oil is facilitated by increasing the amount of power applied to the transducers, thereby increasing the amplitude of the transducer vibrations. Application Ser. No. 09/746,849 discloses a system for increasing the amount of power applied to the transducers by introducing an alternating voltage rich in harmonics (e.g. a square ware voltage) to the transducer. Attempts are being made to increase the ability of the transducers to provide enhanced magnitudes of vibrations without cracking.
In a preferred embodiment of the invention, a transducer has enhanced abilities to provide (a) increased magnitude of vibrations without cracking and (b) increased power to the transducer, in response to alternating voltages, for producing transducer vibrations with increased magnitudes.
The transducer includes a ceramic (e.g. polycrystalline lead titanate or polycrystalline lead zirconate) having a looped configuration with a gap and having properties of vibrating upon an introduction of an alternating voltage, preferably rich in harmonics, to the ceramic. The ceramic is cryogenically treated as by initially reducing its temperature to approximately xe2x88x92100xc2x0 C., then disposing the ceramic in liquid nitrogen and thereafter gradually increasing its temperature to room temperature. This increases the dielectric strength of the ceramic by prestressing the ceramic, thereby providing for the ceramic to receive increased voltages without cracking.
A support member (e.g. steel or aluminum) having a looped configuration, and having a gap aligned with the ceramic gap and having properties of vibrating with the ceramic envelopes and is attached to, the ceramic. The support member may have a substantially uniform thickness around its periphery or a progressively increasing thickness with progressive distances in opposite directions from the gap to enhance its ability to withstand cracking when subjected to vibrations. Instead of providing a ceramic in a loop, the cryogenically treated ceramic may be sectionalized in another embodiment and the sections may be stacked in the space between the opposite legs of the support and attached at their opposite ends to the support legs. In other embodiments a plurality of transducers may be combined in different ways to form a transducer assembly with enhanced power characteristics.